The Tu B'shevat reference article from the English Wikipedia on 24-Apr-2004
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Tu B'shevat

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Tu B'shevat is the Jewish holiday version of Arbor Day. It is the new year for trees. This day was set aside in the Mishnah on which to bring fruit tithes. It is still celebrated in modern times. In the 1600's Land of Israel, Rabbi Yitzchak Luria of Safed (also: Tzefat) and his disciples created a short seder, reminiscent of the seder that Jews observe on Pesach, that explores the holiday's Kabbalistic themes. It is customary on this holiday to eat 14 different servings of fruits.